1. Technical Field
The present invention relates to a power conversion apparatus such as an inverter which is installed in a passenger car, an auto truck or the like.
2. Related Art
A large-capacity inverter, which converts DC power to AC power or AC power to DC power, is required for a hybrid vehicle having both an internal-combustion engine and an electric motor as driving sources, an automobile including an electric motor as a driving source, and the like. Hence, various power conversion apparatuses including an inverter have been developed.
As an example, power conversion apparatuses are known which are disclosed in JP-A-2009-81993 and JP-A-2007-50887. As shown in FIG. 17, a power conversion apparatus 100 is configured by accommodating electronic components including an inverter, and a resin terminal block 102 collecting wires 101 running from the electronic components, in a case 103.
A plurality of through-holes 103a, into which a high-voltage cable 104 is inserted, are formed in one side wall configuring the metal case 103. The high-voltage cable 104 inserted and arranged in the through-hole 103a is fastened to the terminal block 102 together with the wire 101 by using a bolt 106. Hence, electric power can be received to the inside of the case 103 and provided to the outside of the case 103 via the wire 101 and high-voltage cable 104.
In addition, an opening part 105 for inserting the bolt 106 is formed in the case 103. The bolt 106 and a tool such as a screwdriver are inserted from above through the opening part 105 to fasten the high-voltage cable 104 and the wire 101 to the terminal block 102 by using the bolt 106. In addition, a cover 107 is arranged above the opening part 105 to ensure the waterproof property of the case 103. The cover 107 can close the opening part 105 after the high-voltage cable 104 and the wire 101 are fastened to the terminal block 102 by the bolt 106.
In the above-described power conversion apparatus 100, the case 103 and a terminal 104a of an end portion of the high-voltage cable 104 connected to the wire 101 are made of conductors. The case 103 and the terminal 104a are required to have electric potentials different from each other for normal operation. Hence, an insulation distance is required to be ensured between the terminal 104a and a side wall of the case 103. Meanwhile, when the terminal block 102, on which the terminal 104a is mounted for ensuring an insulation distance, is arranged in a state where the terminal block 102 is separated from the case 103, a gap is generated between the terminal block 102 and the case 103. As a result, in a process of fastening the bolt 106, the bolt 106 can be detached from the tool and fall into the case 103 through the gap.
To solve the above problem, in the conventional art, while the terminal 104a is arranged being separated from the case 103, the terminal block 102 is extended from the connection portion between the terminal 104a and the wire 101 toward the case 103 side so as to be close to the side wall of the case 103, so that the bolt 106 does not fall through the gap. Thereby, the bolt 106 is prevented from falling into the back of the case 103 while ensuring an insulation distance.
However, when the terminal block 102 is extended from the connection portion between the terminal 104a and the wire 101 toward the case 103 side, the terminal 104a and the side wall of the case 103 are separated from each other. Hence, to easily retrieve the bolt 106 fallen on the terminal block 102, the area of the opening part 105 is required be made large. However, when the area of the opening part 105 is large, the load applied to the cover 107 becomes large due to the differential pressure between the inside and the outside of the case 103, whereby the sealing property between the case 103 and the cover 107 is lowered. Hence, the number of places where the bolts 106 are fastened is required to be increased to increase the sticking intensity of the cover 107. Conversely, when the area of the opening part 105 is made small, the bolt 106 fallen on the terminal block 102 cannot be seen through the opening part 105, whereby retrieving the bolt 106 can become difficult.